Copyright | (c) The University of Glasgow 2001 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | libraries@haskell.org |
Stability | provisional |
Portability | portable |
Safe Haskell | Safe |
Language | Haskell2010 |
Text.Show
Description
Converting values to readable strings:
the Show
class and associated functions.
Documentation
Conversion of values to readable String
s.
Derived instances of Show
have the following properties, which
are compatible with derived instances of Read
:
- The result of
show
is a syntactically correct Haskell expression containing only constants, given the fixity declarations in force at the point where the type is declared. It contains only the constructor names defined in the data type, parentheses, and spaces. When labelled constructor fields are used, braces, commas, field names, and equal signs are also used. - If the constructor is defined to be an infix operator, then
showsPrec
will produce infix applications of the constructor. - the representation will be enclosed in parentheses if the
precedence of the top-level constructor in
x
is less thand
(associativity is ignored). Thus, ifd
is0
then the result is never surrounded in parentheses; ifd
is11
it is always surrounded in parentheses, unless it is an atomic expression. - If the constructor is defined using record syntax, then
show
will produce the record-syntax form, with the fields given in the same order as the original declaration.
For example, given the declarations
infixr 5 :^: data Tree a = Leaf a | Tree a :^: Tree a
the derived instance of Show
is equivalent to
instance (Show a) => Show (Tree a) where showsPrec d (Leaf m) = showParen (d > app_prec) $ showString "Leaf " . showsPrec (app_prec+1) m where app_prec = 10 showsPrec d (u :^: v) = showParen (d > up_prec) $ showsPrec (up_prec+1) u . showString " :^: " . showsPrec (up_prec+1) v where up_prec = 5
Note that right-associativity of :^:
is ignored. For example,
produces the stringshow
(Leaf 1 :^: Leaf 2 :^: Leaf 3)"Leaf 1 :^: (Leaf 2 :^: Leaf 3)"
.
Methods
Arguments
:: Int | the operator precedence of the enclosing
context (a number from |
-> a | the value to be converted to a |
-> ShowS |
Convert a value to a readable String
.
showsPrec
should satisfy the law
showsPrec d x r ++ s == showsPrec d x (r ++ s)
Derived instances of Read
and Show
satisfy the following:
That is, readsPrec
parses the string produced by
showsPrec
, and delivers the value that showsPrec
started with.
Instances
Show Bool # | |
Show Char # | Since: 2.1 |
Show Int # | Since: 2.1 |
Show Int8 # | Since: 2.1 |
Show Int16 # | Since: 2.1 |
Show Int32 # | Since: 2.1 |
Show Int64 # | Since: 2.1 |
Show Integer # | Since: 2.1 |
Show Natural # | Since: 4.8.0.0 |
Show Ordering # | |
Show Word # | Since: 2.1 |
Show Word8 # | Since: 2.1 |
Show Word16 # | Since: 2.1 |
Show Word32 # | Since: 2.1 |
Show Word64 # | Since: 2.1 |
Show RuntimeRep # | |
Show VecCount # | |
Show VecElem # | |
Show CallStack # | Since: 4.9.0.0 |
Show SomeTypeRep # | Since: 4.10.0.0 |
Show () # | |
Show TyCon # | Since: 2.1 |
Show Module # | Since: 4.9.0.0 |
Show TrName # | Since: 4.9.0.0 |
Show KindRep # | |
Show TypeLitSort # | |
Show SrcLoc # | |
Show SomeException # | Since: 3.0 |
Show GeneralCategory # | |
Show Number # | |
Show Lexeme # | |
Show Fingerprint # | Since: 4.7.0.0 |
Show IOMode # | |
Show IntPtr # | |
Show WordPtr # | |
Show CUIntMax # | |
Show CIntMax # | |
Show CUIntPtr # | |
Show CIntPtr # | |
Show CSUSeconds # | |
Show CUSeconds # | |
Show CTime # | |
Show CClock # | |
Show CSigAtomic # | |
Show CWchar # | |
Show CSize # | |
Show CPtrdiff # | |
Show CDouble # | |
Show CFloat # | |
Show CBool # | |
Show CULLong # | |
Show CLLong # | |
Show CULong # | |
Show CLong # | |
Show CUInt # | |
Show CInt # | |
Show CUShort # | |
Show CShort # | |
Show CUChar # | |
Show CSChar # | |
Show CChar # | |
Show SomeNat # | Since: 4.7.0.0 |
Show SomeSymbol # | Since: 4.7.0.0 |
Show DecidedStrictness # | |
Show SourceStrictness # | |
Show SourceUnpackedness # | |
Show Associativity # | |
Show Fixity # | |
Show Any # | |
Show All # | |
Show ArithException # | Since: 4.0.0.0 |
Show ErrorCall # | Since: 4.0.0.0 |
Show IOException # | Since: 4.1.0.0 |
Show MaskingState # | |
Show CodingProgress # | |
Show TextEncoding # | Since: 4.3.0.0 |
Show SeekMode # | |
Show NewlineMode # | |
Show Newline # | |
Show BufferMode # | |
Show Handle # | Since: 4.1.0.0 |
Show IOErrorType # | Since: 4.1.0.0 |
Show ExitCode # | |
Show FixIOException # | |
Show ArrayException # | Since: 4.1.0.0 |
Show AsyncException # | Since: 4.1.0.0 |
Show SomeAsyncException # | Since: 4.7.0.0 |
Show AssertionFailed # | Since: 4.1.0.0 |
Show CompactionFailed # | Since: 4.10.0.0 |
Show AllocationLimitExceeded # | Since: 4.7.1.0 |
Show Deadlock # | Since: 4.1.0.0 |
Show BlockedIndefinitelyOnSTM # | Since: 4.1.0.0 |
Show BlockedIndefinitelyOnMVar # | Since: 4.1.0.0 |
Show CodingFailureMode # | |
Show Fd # | |
Show CClockId # | |
Show CSsize # | |
Show CPid # | |
Show COff # | |
Show CMode # | |
Show CIno # | |
Show CDev # | |
Show Dynamic # | Since: 2.1 |
Show ThreadStatus # | |
Show BlockReason # | |
Show ThreadId # | Since: 4.2.0.0 |
Show NestedAtomically # | Since: 4.0 |
Show NonTermination # | Since: 4.0 |
Show TypeError # | Since: 4.9.0.0 |
Show NoMethodError # | Since: 4.0 |
Show RecUpdError # | Since: 4.0 |
Show RecConError # | Since: 4.0 |
Show RecSelError # | Since: 4.0 |
Show PatternMatchFail # | Since: 4.0 |
Show ConsoleEvent # | |
Show FileLockingNotSupported # | |
Show HandlePosn # | Since: 4.1.0.0 |
Show Version # | |
Show ByteOrder # | |
Show GCDetails # | |
Show RTSStats # | |
Show RTSFlags # | |
Show ParFlags # | |
Show TickyFlags # | |
Show TraceFlags # | |
Show DoTrace # | |
Show ProfFlags # | |
Show DoHeapProfile # | |
Show CCFlags # | |
Show DoCostCentres # | |
Show DebugFlags # | |
Show MiscFlags # | |
Show ConcFlags # | |
Show GCFlags # | |
Show GiveGCStats # | |
Show Fixity # | |
Show ConstrRep # | |
Show DataRep # | |
Show Constr # | Since: 4.0.0.0 |
Show DataType # | |
Show StaticPtrInfo # | |
Show Void # | Since: 4.8.0.0 |
Show a => Show [a] # | Since: 2.1 |
Show a => Show (Maybe a) # | |
Show a => Show (Ratio a) # | Since: 2.0.1 |
Show (Ptr a) # | Since: 2.1 |
Show (FunPtr a) # | Since: 2.1 |
Show p => Show (Par1 p) # | |
Show a => Show (NonEmpty a) # | |
Show a => Show (Down a) # | Since: 4.7.0.0 |
Show a => Show (Product a) # | |
Show a => Show (Sum a) # | |
Show a => Show (Dual a) # | |
Show a => Show (Last a) # | |
Show a => Show (First a) # | |
Show (ForeignPtr a) # | Since: 2.1 |
Show a => Show (Identity a) # | This instance would be equivalent to the derived instances of the
Since: 4.8.0.0 |
Show a => Show (ZipList a) # | |
Show a => Show (Option a) # | |
Show m => Show (WrappedMonoid m) # | |
Show a => Show (Last a) # | |
Show a => Show (First a) # | |
Show a => Show (Max a) # | |
Show a => Show (Min a) # | |
HasResolution a => Show (Fixed a) # | Since: 2.1 |
Show a => Show (Complex a) # | |
(Show a, Show b) => Show (Either a b) # | |
Show (V1 p) # | Since: 4.9.0.0 |
Show (U1 p) # | Since: 4.9.0.0 |
Show (TypeRep a) # | |
(Show a, Show b) => Show (a, b) # | Since: 2.1 |
Show (ST s a) # | Since: 2.1 |
Show (Proxy s) # | Since: 4.7.0.0 |
(Show a, Show b) => Show (Arg a b) # | |
Show (f p) => Show (Rec1 f p) # | |
Show (URec Word p) # | |
Show (URec Int p) # | |
Show (URec Float p) # | |
Show (URec Double p) # | |
Show (URec Char p) # | |
(Show a, Show b, Show c) => Show (a, b, c) # | Since: 2.1 |
Show (a :~: b) # | |
Show (Coercion a b) # | |
Show (f a) => Show (Alt f a) # | |
Show a => Show (Const a b) # | This instance would be equivalent to the derived instances of the
Since: 4.8.0.0 |
Show c => Show (K1 i c p) # | |
(Show (f p), Show (g p)) => Show ((f :+: g) p) # | |
(Show (f p), Show (g p)) => Show ((f :*: g) p) # | |
(Show a, Show b, Show c, Show d) => Show (a, b, c, d) # | Since: 2.1 |
Show (a :~~: b) # | Since: 4.10.0.0 |
(Show1 f, Show1 g, Show a) => Show (Sum f g a) # | Since: 4.9.0.0 |
(Show1 f, Show1 g, Show a) => Show (Product f g a) # | Since: 4.9.0.0 |
Show (f p) => Show (M1 i c f p) # | |
Show (f (g p)) => Show ((f :.: g) p) # | |
(Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e) # | Since: 2.1 |
(Show1 f, Show1 g, Show a) => Show (Compose f g a) # | Since: 4.9.0.0 |
(Show a, Show b, Show c, Show d, Show e, Show f) => Show (a, b, c, d, e, f) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g) => Show (a, b, c, d, e, f, g) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h) => Show (a, b, c, d, e, f, g, h) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i) => Show (a, b, c, d, e, f, g, h, i) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j) => Show (a, b, c, d, e, f, g, h, i, j) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k) => Show (a, b, c, d, e, f, g, h, i, j, k) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l) => Show (a, b, c, d, e, f, g, h, i, j, k, l) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n) # | Since: 2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n, Show o) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) # | Since: 2.1 |
showChar :: Char -> ShowS Source #
utility function converting a Char
to a show function that
simply prepends the character unchanged.
showString :: String -> ShowS Source #
utility function converting a String
to a show function that
simply prepends the string unchanged.
showListWith :: (a -> ShowS) -> [a] -> ShowS Source #
Show a list (using square brackets and commas), given a function for showing elements.